<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>节流</title>
  <style>
    body {
      height: 2000px;
    }
  </style>
</head>

<body>
  <script>
    // 节流：控制高频事件的触发次数
    window.onscroll = throttle(function () {
      console.log('页面滚动');
    }, 500);

    // 封住节流代码
    function throttle(fn, delay) {
      let flag = true;
      return function () {
        if (flag) {
          setTimeout(() => {
            fn.call(this)
            flag = true
          }, delay)
        }
        flag = false
      }
    }
  </script>
</body>

</html>